A Portable, Accurate, Low-Cost, Open Source Air Particle Counter

If you live in a city with poor air quality you may be aware that particulates are one of the chief contributors to the problem. Tiny particles of soot from combustion, less than 10μm across, hence commonly referred to as PM10. These are hazardous because they can accumulate deep in the lungs, wherein all kinds of nasties can be caused.

There are commercial sensors available to detect and quantify these particles, but they are neither inexpensive nor open source. [Rundong] tells us about a project that aims to change that situation, the MyPart, which is described as a portable, accurate, low-cost, open source air particle counter. There is a GitHub repository for the project as well as a series of Instructables covering the build in detail. It comes from a team of members of the Hybrid Ecologies Lab at UC Berkeley, USA.

Along the way, they provide a fascinating description of how a particulate sensor works. A laser shines at right angles across a photodiode, and is brought to a focal point above it. Any particulates in the air will scatter light in the direction of the photodiode, which can thus detect them. The design of a successful such sensor requires a completely light-proof chamber carefully built to ensure a laminar flow of air past laser and diode. To that end, their chamber has several layers and is machined rather than 3D-printed for internal smoothness.

We’ve covered quite a few environmental sensors over the years here at Hackaday. An open source volatile organic compound (VOC) detector featured last year for example, or this Raspberry Pi-based  system using a commercial gas sensor.

Air Quality Sensors in Every Classroom

One of the first electronics projects for the aspiring hobbyist is wiring a sensor of some sort to a microcontroller, and then doing something useful with the new information. [Brock] has taken this type of gateway project and turned it into a way to get his students involved and familiar with electronics. His take on an air quality meter accomplishes both of these goals, and hopefully helps turn all of his students into the next generation of hackers.

The bill of materials is pretty straightforward. Instead of the go-to Arduino, [Brock] has gone with a Particle Photon which has the added benefits of various wireless connectivity options. The air quality sensor is a Shinyei PP42ns which interfaces easily with the Photon. The only thing that might be out of reach of most public high schools (at least in the United States) is the 3D-printed enclosure, although if you have access to one, [Brock] put the files on the project page so anyone can use them.

Of course, we’re big fans of projects that get students involved in anything beyond standardized tests, and this project goes a long way towards teaching students more than how to pass a test. There are many videos and instructions on the project page if you want to try this on your own, but if the cost for the materials is the only thing scaring you off from doing this in your own classroom there are a few other options. You could use ATtiny chips, or try a different style of sensor, or maybe just try out a different project altogether.

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DIY Air Quality Meter And Emissions Tester

Handheld measuring devices make great DIY projects. One can learn a lot about a sensor or sensor technology by just strapping it onto a spare development board together with an LCD for displaying the sensor output. [Richard’s] DIY air quality meter and emissions tester is such a project, except with the custom laser-cut enclosure and the large graphic LCD, his meter appears already quite professional.

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Air Quality Surveillance for Whole Cities

Air quality is becoming a major issue these days, and not just for cities like Beijing and Los Angeles. It’s important for health, our environment, and our economy no matter where we live. To that end, [Radu] has been working on air quality monitors that will be widely deployed in order to give a high-resolution air quality picture, and he’s starting in his home city of Timisoara, Romania.

[Radu] built a similar device to measure background radiation (a 2014 Hackaday Prize Semifinalist), and another to measure air quality in several ways (a 2015 Hackaday Prize Finalist and a Best Product Finalist; winners will be announced next weekend). He is using the platforms as models for his new meter. The device will use a VOC air sensor and an optical dust sensor in a mobile unit connected to a car to gather data, and from that a heat map of air quality will be generated. There are also sensors for temperature, pressure, humidity, and background radiation. The backbone of the project is a smart phone which will upload the data to a server.

We’ve seen other air quality meters before as well, and even ones based around the Raspberry Pi,  but this one has a much broader range of data that it is acquiring. Its ability to be implemented as an array of sensors to gather data for an entire city is impressive as well. We can envision sensor networks installed on public transportation but to get to all parts of every neighborhood it would be interesting to team up with the Google Streetview Cars, Uber, or UPS.

Watch those VOCs! Open Source Air Quality Monitor

Ever consider monitoring the air quality of your home? With the cost of sensors coming way down, it’s becoming easier and easier to build devices to monitor pretty much anything and everything. [AirBoxLab] just released open-source designs of an all-in-one indoor air quality monitor, and it looks pretty fantastic.

Capable of monitoring Volatile Organic Compounds (VOCs), basic particulate matter, carbon dioxide, temperature and humidity, it takes care of the basic metrics to measure the air quality of a room.

Exploded CAD View

All of the files you’ll need are shared freely on their GitHub, including their CAD — but what’s really awesome is reading back through their blog on the design and manufacturing process as they took this from an idea to a full fledged open-source device.

Did we mention you can add your own sensors quite easily? Extra ports for both I2C and analog sensors are available, making it a rather attractive expandable home sensor hub.

To keep the costs down on their kits, [AirBoxLab] relied heavily on laser cutting as a form of rapid manufacturing without the need for expensive tooling. The team also used some 3D printed parts. Looking at the finished device, we have to say, we’re impressed. It would look at home next to a Nest or Amazon Echo. Alternatively if you want to mess around with individual sensors and a Raspberry Pi by yourself, you could always make one of these instead.

Gas sensor suite built with Gadgeteer modules

gadgeteer-gas-sensor-suite

[Blake] just finished a gas sensor suite built from Gadgeteer parts. The three sensors are the cylindrical towers along the left hand side of the assembly. The one at the top (with the orange ring) is an alcohol sensor. The middle one senses ammonia and the lower sensor measures air quality. Also rolled into the mix are temperature and humidity sensors.

You can collect a lot of data with this type of setup. To keep it organized [Blake] used the ThingSpeak interface. Using the NIC in the upper right he uploads the measurements for real-time graphing. The setup is explained in detail in the video after the break, including a test with some cleaning ammonia.

We haven’t tried out the Gadgeteer system for ourselves yet. But you’ve got to admit that the ribbon cable connector system the family of parts uses really helps to keep a rather complicated setup like this one nice and tidy.

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Standalone air quality monitor based around Raspberry Pi

rpi-air-quality-monitor

You can have a lot of fun tinkering with the Raspberry Pi. But in addition to the low-cost hobby potential it is actually a great choice for serious data harvesting. This air quality monitor is a great example of that. The standalone package can be taped, screwed, bolted, or bungeed at the target location with a minimum of effort and will immediately start generating sample data.

The enclosure is a weather proof electrical box. The RPi board is easy to spot mounted to the base of the case. On the lid there is an 8 Ah battery meant to top off an iPhone. It works perfectly as it provides a USB port and enough current to operate the Pi. On top of that battery is a 3G modem used to access the data remotely — although it can log to the SD card for collection at a later time if you’d rather not mess with a cell network.

Look closely at the GPIO header and you’ll notice that an ADC add-on board has been plugged in. This is used to take the readings from the gas sensor which is monitoring for air pollutants in Paris.